We are in constant movement. The Earth revolves around its axis at about 1,600 km / h, and around the Sun at about 100,000 km / h. The Sun revolves around the center of our galaxy (the Milky Way) at about 850,000 km / h, taking about 200 million years to complete a lap. In turn, it has been determined that the Milky Way moves, with respect to the rest of the expanding universe, to about 2 million km / h. But what drives the Milky Way in its movement?
This topic is the study that is news today. A team of cosmologists from the Hebrew University of Jerusalem has gone one step further in the intricate process of answering this question, and their results have just been published in the journal Nature. It seems that the Milky Way, along with its accompanying galaxies, are under the joint influence of a repulsion and an attraction.
When we talk about the large-scale structure of the Universe it is easy to get lost. We can summarize the situation as follows:
Our galaxy, the Milky Way, belongs to a superior structure, the cluster of galaxies we call the Local Group. It is made up of about 30 galaxies, and the Milky Way is one of the largest of the cluster - along with Andromeda and the galaxy of the Triangle. It is part of an even larger structure, the supercluster of Virgo galaxies. In 2014 began to talk about another superstructure that began to be called "Laniakea" (sky immeasurable, in Hawaiian). It is a region that groups four large superclusters, among which is ours. But like other similar regions formed by aggregates of several superclusters, it is neither gravitationally compacted nor perfectly defined. Laniakea heads for the Great Shapley Supercluster, and it is speculated that both superclusters may form part of a larger complex. Other great superclusters, apart from the supercluster of Shapley, are: Hercules, Coma and the supercluster of Perseus-Pisces. These superstructures form filaments and leave voids, giving the structure of the universe on a large scale the appearance of a large cosmic web.
Until now, the Milky Way and the Local Group were supposed to be attracted to a denser region of the Universe, towards which we "fell". The first suspect to be the creator of this attraction was called Great Attractor, and it was a region containing half a dozen galaxy clusters about 150 million light-years. Later, attention was focused on an even larger area, with more than two dozen rich clusters, called the Shapley Concentration or Shapley Supercluster, located 600 million light-years beyond the Great Attractor and to which we have already referred. But there was one problem: even though Shapley's supercluster is incredibly massive, it can not by itself explain the speed at which the Milky Way is shifting.
Now, researchers led by Yehuda Hoffman tell us that our galaxy is not only being attracted to this region, but also being pushed by another region of our neighborhood - 500 million light-years away from us. It is an area quite devoid of galaxies, almost empty - a void of the cosmic web. This is what they have called the Repulsor Dipole.
Using data from large telescopes and at different wavelengths, including the Hubble Space Telescope, they have developed a 3D map with the flow field of galaxies (their velocities, where they move). Combining it with other data, they have been able to infer the associated underlying mass distribution. Data from more than 8,000 nearby galaxies fit neatly into what appears to be our cosmic neighborhood, and its motions provide us with the first real evidence of the existence of the great Dipole Repulsor. As seen in the attached video.
In other words, by identifying the Repulsor Dipole, the researchers have been able to reconcile both the direction of motion of the Milky Way and its magnitude - too large to be due only to the Shapley attractor. And, with future ultra-sensitive optical, infrared and radio observations, they hope to identify the few galaxies that are expected to be inside this vacuum, and thus directly confirm the vacuum associated with the Repulsor Dipole.
If its existence is confirmed, it will be necessary to answer the new question of the million: What the hell is that emptiness-Dipole Repulsor?
watch video:
Source: http://irfu.cea.fr/dipolerepeller
Credits pictures: Flow-antiflow illustration, courtesy of The Hebrew University of Jerusalem.
Credit: Daniel Pomarède